MKS Micro-Baratron 870B, Instruction Manual, Page: 54 / 68

How To Adjust the Zero Chapter Four: Operation
44
To properly zero the 870/872 transducer:
1. Install the 870/872 transducer in a system and connect a power supply/readout.
2. Power the transducer and allow it to stabilize.
Note Ensure that the transducer is fully stabilized before you adjust the zero.
3. Pump the unit down to a pressure one decade below its resolution (0.001% of FS).
For best results, pump the transducer while it is warming up. Refer to Table 14 for the
highest recommended pressure levels for proper zero adjustment.
Highest Pressures Suggested for Proper Zero Adjustment
Full Scale Range Highest Pressure for Proper Zero Adjustment
1000 Torr 0.010 Torr
100 psia 0.0010 psia
250 psia 0.0025 psia
1000 psia 0.0100 psia
3000 psia 0.0300 psia
Table 14: Highest Pressures Suggested for Proper Zero Adjustment
4. Adjust the
ZERO
pot with a small flathead screwdriver until the readout displays zero
(0000).
The
ZERO
pot is located on the side of the transducer body (refer to Figure 1, page 25,
and Figure 3, page 27.
Note In 4 to 20 mA units, the
ZERO
pot adjusts the 4 mA setting.